Amorphous silica particles and methods of producing amorphous silica particles

ABSTRACT

An amorphous silica particles, gravel, other particles and products provide a safe replacement for crystalline silica sand, grave, or particles in consumer and industrial applications wherein dust may be produced during use or installation. The amorphous silica particles, gravel, other particles or products may comprise components that increase the density, hardness, and other properties from container glass. These components include, but are not limited to, iron oxides, aluminum oxides, and zirconium oxides.

RELATED APPLICATION

This application claims priority to U.S. provisional patent applicationNo. 62/620,570 filed on Jan. 23, 2018 which is hereby incorporated byreference.

TECHNICAL FIELD

Embodiments of the method of invention comprise producing amorphoussilica glass particles directly from natural crystalline silica sand.Natural silica sand is comprised almost entirely of the crystalline formof the silica. However, airborne crystalline silica has been determinedto be a hazardous substance that has been shown to cause silicosis ifinhaled.

Embodiments of a method include heating crystalline silica sand, gravel,or other particles to a temperature in which the crystalline silica isconverted into amorphous silica sand, gravel, or other particles. Theamorphous silica particles, gravel, or other particles may be used as asafe replacement for crystalline silica sand, gravel, or particles inconsumer and industrial applications wherein dust may be produced duringuse or installation, for example.

In another embodiment, the crystalline silica sand may be heated in thepresence of fluxing components, density increasing components, hardnessincreasing components and other property enhancing components. Thedensity increasing components may be aluminum oxide, zirconium oxide,days comprising aluminum oxide, zirconium oxide, or a combination ofaluminum oxide, iron oxide, and zirconium oxide. Other densityincreasing components include titanium oxide and other transition metaloxides.

In a still further embodiment, an enhanced glass product may beproduced. The

Thermal (fuse or melt) processing of crystalline-silica containingminerals (comprising quartz sands and heavy mineral sands) and,optionally, recycled glass streams assure the conversion of theircrystalline silica content into amorphous silica sands, gravel, or otherparticles and, also, kills any microbes present in the feed streams.Therefore, the amorphous silica products are microbe free.

Embodiments also include products produced from the amorphous silicasand, gravel or other particles. For example, embodiments of theproducts include crystalline silica free sand, gravel, cullet, blastingabrasives, concrete mixes, grout, manufactured stone, mortar, bricks,concrete blocks, other concrete products, pavers, and other productsthat would benefit and safer with the replacement of crystalline silicawith amorphous silica. The amorphous silica products may be a directreplacement for the crystalline silica products.

BACKGROUND

Crystalline silica is the most abundant mineral on earth. Due to itsabundance and low cost, crystalline silica sand, gravel, and rocks havebeen used for many industrial and consumer applications. Includinghydraulic fracturing sand, glass production, foundry sand, buildingmaterials, sand blasting, recreational sand, as well as other uses.Gravel or coarse aggregate shall herein be defined as any aggregatelarger than about 3/16 of an inch. Sand or fine aggregate is defined asany aggregate less than about 3/16 of inch with silt being consideredthe smallest particles.

However, it has been found that airborne particles of crystalline silicasand may enter the lungs of people in and around any area. Crystallinesilica sand in the lungs may result in the development of silicosis anda host of other illnesses. Silicosis is one of the world's oldest knownoccupational diseases, with reports of employees contracting the diseasedating back to ancient Greece.

Airborne crystalline silica dust may be produced during themanufacturing process of the crystalline silica products and also duringuse or installation of the crystalline silica products. For example,crystalline silica dust becomes airborne, such as during blasting withsand and cutting concrete or bricks, for example.

Abrasive blasting uses compressed air or water to direct a high velocitystream of an abrasive material to clean an object or surface, removeburrs, apply a texture or prepare a surface for painting. Abrasiveblasting is more commonly known as sandblasting since silica sand iscommonly used as the abrasive, although not the only one always used,industries that rely on sandblasting on a daily or regular basis includepainting who work on large structures like bridges, granite monumentmakers, foundries and shipbuilders. Industries that rely on sandblastingon a daily or regular basis include any one doing surface preparationwork or restoration on large structures like bridges, tanks, pipelines,heavy equipment, shipbuilders, or concrete restoration.

The term “silica” broadly refers to the mineral compound silicon dioxide(SiO2). Although silica can be crystalline or amorphous in form, onlythe natural crystalline form of silica is hazardous to users that mayinhale crystalline silica dust. Owing to its abundance, unique physicaland chemical properties, crystalline silica has many uses. Common,commercially produced silica products include quartzite, tripoli,gannister, chert, and novaculite. Crystalline silica also occurs innature as agate, amethyst, chalcedony, cristobalite, flint, quartz,tridymite, and, in its most common form, silica sand.

Silica sand has been used for many products throughout human history,but one of its most common use is in the production of glass. Table 1-1summarizes other uses for sand and gravel. In some instances, grindingof sand, gravel, or products containing crystalline silica sand orgravel is required, producing and Increasing levels of dust containinghazardous respirable crystalline silica.

TABLE 1 Typical uses of silica sand and gravel Product Major End UseSand Glass Containers, flat (plate and window), specialty, fiberglassMaking (un-ground or ground) Foundry Molding and core, molding and corefacing (ground) refractory Metallurgical Silicon carbide, flux for metalsmelting Abrasives Blasting, scouring cleaners (ground), sawing andsanding, chemicals (ground and un-ground) Fillers Rubber, paints, putty,whole grain fillers/building products Ceramic Pottery, brick, tile, andrefractory ceramics Filtration Water (municipal, county, local),swimming pool, others Petroleum Hydraulic fracturing, well packing, andcementing industry Recreational Golf courses, baseball, volleyball playsands, beaches, traction (engine), roofing granules and fillers, other(ground silica or whole grain) Gravel Silica, ferrosilicon, filtration,nonmetallurgical flux, other

In March 2016, tire Occupational Safety and Health Administration (OSHA)issued a final rule to requiring companies to control exposure torespirable crystalline silica. The rule is comprised of two standards:one for Construction (29 Code of Federal Regulations (CFR) 1926.1153)and the other for General Industry (29 CFR 1930.1053) and Maritime (23CFR 1915.1053). The Maritime and General Industry standards are thesimilar, but differ from the Construction standard. The GeneralIndustry/Maritime Standard requires the employer to perform airmonitoring to determine the eight-hour average exposure level for eachaffected job task. Employers governed by the Construction standard caneither use a control method spelled out for common construction worktasks or perform air monitoring as detailed in the GeneralIndustry/Maritime standard.

These requirements can be expensive to implement. To use crystallinesilica in the workplace, worker protective measures need to be taken.Initially, airborne crystalline silica sampling needs to be conducted.Once collected, the samples are sent to a laboratory for analysis. Theresults of this analysis will determine if improved ventilation and/or achange in work practices or respiratory protection is needed.

The new action limit and permissible exposure limit (PEL) forcrystalline silica for General Industry, Construction and Maritime areall the same and can be found in Construction (29 CFR 1926.1153),General Industry (29 CFR 1910.1053) or Maritime (29 CFR 1915.1053). Theaction limit is established at 25 micrograms per cubic meter (ug/m3) andthe PEL is established at 50 ug/m3.

To help control the risk of respirable crystalline silica exposure,OSHA's “three lines of defense” philosophy is suggested The first fineof defense is to eliminate and/or engineer the crystalline silicaexposure hazard out. This may be best performed by removing thecrystalline silica from the workplace. When engineering/animationcontrols are not feasible or practical, the second and third fines ofdefense can be used to help control the crystalline silica exposurehazard. The second line of defense is administrative controls, and thelast line of defense to be considered is personal protective equipment(PPE).

OSHA recommends the first engineering control to consider issubstitution of the crystalline silica with a nonhazardous product. OSHAsuggests using a less toxic abrasive blasting media that can bedelivered with water to reduce dust generation. This creates the needfor a suitable substitution for the crystalline silica.

The advantages of using a silica substitute outweigh using silica inabrasive sandblasting due to the hazards and compliance with theregulations The health issues and healthcare costs related to silicawould be greatly reduced or eliminated. The time and cost ofimplementing and maintaining engineering controls would also beeliminated. The disadvantages are that the existing substitutes may notbe as hard as a crystalline silica abrasive, nor as dense. Therefore,more of the substitute may need to be used to achieve the same result.It may also be more expensive.

There is a need for a safe substitute for crystalline silica productsthat do not cause silicosis and do not require strict engineeringcontrols for safe use. There is a further need for an inexpensive,effective amorphous silica sand and amorphous silica gravel forcommercial and residential products, including for use as a blastingmedium. There is a further need for a water-soluble amorphous Silicaproduct.

SUMMARY

Embodiments of the amorphous silica products comprise higherconcentrations of metal oxides, such as, but not limited to, iron oxide,alumina, and zirconia, for example. The concentrations of metal oxidesresult in an amorphous silica product with a density and hardness abovethe density and hardness amorphous silica or typical recycled glass. Theamorphous silica product may be substantially free of deleterious levelsof toxic or heavy metals. As used herein, the term “substantially freeof deleterious levels of toxic or heavy metals” means that theenvironmental and industrial hygiene organizations do not consider theamorphous silica product toxic if used as intended.

An embodiment of an amorphous silica product for use as an abrasives,proppants, and sand/sanded products such as, but not limited to, grouts,mortars and concrete, for example, may comprise silicon oxide in therange of 56 wt. % to 80 wt. %, iron oxides in the range of 5 wt. % to 35wt. %, aluminum oxides in the range of 0 wt. % to 8 wt. %, zirconiumoxides in the range of 0 wt. % to 5 wt. %, and modifiers in the range of0 wt. % to 10 wt. %. Embodiments of the amorphous silica productsincluding the abrasives, proppants, and sand/sanded products may requirethe amorphous silica products to be ground to particles. Therefore,embodiments of the amorphous silica products are particles that havebeen classified into particle size ranges. The embodiments includeparticles that have a bulk composition consisting essentially of siliconoxide in the range of 56 wt. % to 80 wt. %, iron oxides in the range of5 wt. % to 35 wt. %, aluminum oxides in the range of 0 wt. % to 8 wt. %,zirconium oxides in the range of 0 wt. % to 5 wt. %, and modifiers inthe range of 0 wt. % to 10 wt. %.

The oxides may comprise oxides in multiple forms or valences such asferric and ferrous oxides. The glass batches may be melted comprisingvarious form of the metals such as oxides or silicates, for example, butthe amorphous silica product is reported as oxides.

The density of embodiments of certain embodiments of the amorphoussilica products is correlated with increasing concentrations of metaloxides including but not limited to, iron oxides, zirconium oxides,aluminum oxides, and combinations thereof, for example. Embodiments ofthe amorphous silica products may have a density in the range of 2.5g/cc to 3.5 g/cc. Embodiments with higher concentrations of iron oxideand/or other metal oxides may have a density in the range of 2.8 g/cc to3.5 g/cc.

An embodiment of an amorphous silica product for use as abrasives,proppants, and sand/sanded products such as, but not limited to, grouts,mortars and concrete, for example, may comprise silicon oxide in therange of 56 wt. % to 80 wt. %, iron oxides in the range of 10 wt. % to45 wt. %, aluminum oxides in the range of 0 wt. % to 8 wt. %, zirconiumoxides in the range of 0 wt. % to 5 wt. %, and modifiers in the range of0 wt. % to 10 wt. %. The modifier may be typical fluxes used in glassmanufacturing, for example. The embodiments of the amorphous silicaproduct for use as abrasives, proppants, and sand/sanded products may becrushed and classified into particle size ranges. Abrasives, proppantsand sands/sanded products are typically classified into differentparticle size ranges based upon the intended application.

Further, the hardness of embodiments of the amorphous silica product iscorrelated with increasing iron oxides, zirconium oxides, aluminumoxides, and combinations thereof. Embodiments of the amorphous silicaproduct have a Knoop hardness in the range of 615 Hk to 850 Hk.Embodiments with higher concentrations of the metal oxides may have aKnoop hardness in the range of 750 Hk to 850 Hk.

Certain embodiments of the method comprise converting sand, gravel,other minerals and rock naturally comprise converting crystalline orpolycrystalline silica (hereinafter, “crystalline silica”) to anamorphous glass sand or gravel. For example, the crystalline silicasand, gravel, other particles, and/or mineral include, but are notlimited to, silica sand, silica gravel, quartz sand, any type of heavymineral sand including garnet, staurolite, and olivine, for example. Theamorphous glass sand or gravel may be used in or converted to thecommercial and residential applications as described herein.

Embodiments of the method of producing amorphous silica sand or otherproducts comprises converting material comprising crystalline silicainto an amorphous glass sand or gravel or other amorphous product. Theconversion may be performed by heating the crystalline silica to atemperature above the temperature that results in the phase change to anamorphous form of silica. In certain embodiments, this temperature maybe above the melting temperature of crystalline silica. The meltingpoint of pure silica dioxide is approximately 3110° F. (1710° C.). Themelting point may vary based upon the natural composition of the sand,gravel or other rock.

As stated, the melting point of pure silica dioxide is high relative toother materials and processing may be difficult. The melting point of aglass batch comprising crystalline silicas may be, and typically is,lowered by addition of melting temperature reducing agents (fluxes).Thus, in other embodiments, a glass patch may be prepared by mixing thecrystalline silica with a melting point reducing agent.

Further, the density of pure amorphous silica may be too low for someapplications, such as for an effective abrasive blasting medium.Abrasive blasting media may generally be classified by their specificgravity and hardness. Some properties of the media will affect theefficiency of abrasives in removing coatings or cleaning surfacesincluding hardness and density, for example. Generally, the greater thedifference in hardness between the abrasive media and the coating to beremoved or material to be cleaned, the more efficient the blastingprocess. Higher density particles may also result in a more efficientblasting process because higher density particles with similar contactvelocity as lower density particles of approximately the same size willgenerally have a greater contact force and, therefore, result in a moreefficient stripping or cleaning process.

Additionally, a method of producing a water-soluble amorphous silicasand, gravel or other particles may comprise mixing at least one fluxwith the crystalline silica dioxide containing material. Embodiments ofthe method may comprise mixing a flux or fluxes with the silica dioxidecontaining material wherein at least one of the flux or fluxes mix withthe silica dioxide containing material to increase at least one of thedensity and the hardness of the resulting amorphous Silica productrelative to pure amorphous silica or container glass.

Metals and metal oxides may be used as fluxes for crystalline silicadioxide that would result in an amorphous glass product with increaseddensity and/or increased hardness. More conventional glass fluxes mayalso be added.

Embodiments include abrasive blasting media and methods of producingabrasive blasting media. Embodiments of the method for producingamorphous silica abrasive blasting materials eliminate the step ofcollecting, cleaning, and classifying recycled or waste glass. As such,embodiments of the process comprise transforming crystalline orpolycrystalline sand, gravel other particles, or rock that comprisecrystalline silica into amorphous sand, gravel, other particles, or rockto reduce the concentration of crystalline silica (a known carcinogen)to safer levels when the amorphous silica sand, gravel or other particleis manufactured or used. Thus, embodiments of the method comprise makingthese products into a more industrial hygiene friendly substitution fornaturally occurring products containing various forms of crystallinesilica.

In another embodiment, the process for producing amorphous productsconsists essentially of heating sand and/or a mineral comprisingcrystalline silica into an amorphous mass, cooling the amorphous mass toa solid, and forming particles comprising amorphous silica. Theparticles of amorphous silica may be further crushed or otherwisecomminuted to reduce the size of the particles or produce particleshaving a narrower particle size distribution, for example.

An embodiment of the amorphous silica product or abrasive blasting mediacomprises silicon oxide in the range of 50 wt. % to 75 wt. %, metals ormetal oxides in the range of 20 wt. % to 45 wt. %, and other fluxingcompounds in the range of 0 to 10 wt. %. In some embodiments, the otherflux compounds or fluxing compounds do not include the metal oxides. Themetal oxides include, but are not limited to, iron oxides, aluminumoxides, zirconium oxides, titanium oxides, manganese oxides, magnesiumoxides, and combinations-thereof. The metal oxides may be added fromclays, rock, and/or miners containing silicates, oxides, or other formsof these metals.

Metals may also be added in their pure metal form or as an alloy. Themetals include, but are not limited to, iron, aluminum, titanium,zirconium, manganese, magnesium, alloys and combinations thereof. Themetals may be melted in a furnace in the presence of oxygen to at leastpartially form oxides or in a furnace with an inert atmosphere to meltdirectly into the amorphous silica.

For example, an embodiment of the amorphous silica product or abrasiveblasting media comprises silicon oxide in the range of 50 wt. % to 75wt. %, iron oxides in the range of 15 wt. % to 45 wt. %, and otherfluxing compounds in the range of 0 to 10 wt. %. To further reduce themelting point, the other fluxes may be in the range of 1 wt. % to 10 wt.%. This embodiment of the amorphous silica product may comprise aluminumoxides in the range of 0.5 wt. % to 10 wt. %, zirconium oxides in therange of 0.5 wt. % to 10 wt. %, or a combination thereof.

The fluxing compounds may include any fluxes typically used in glassmanufacturing and may include, but are not limited to, sodium oxides,calcium oxides, magnesium oxides, potassium oxides, lithium oxides,boric oxides, and combinations thereof.

In some embodiments, the amorphous silica product or abrasive blastingmedia may comprise a ratio of Si to Fe in the amorphous silica productor abrasive blasting media is in the range of 3:4 to 4:1. Otherembodiments, the ratio of Si to Fe in the range of 3:4 to 3:1. In otherembodiments, the amorphous silica product may comprise a ratio of Si tothe total of Fe and Al in the range of 3:4 to 3:1. In anotherembodiments, the amorphous silica product may comprise a ratio of Si tothe total of Fe and Zr in the range of 3:4 to 3:1. In anotherembodiments, the amorphous silica product may comprise a ratio of Si tothe total of Fe, Zr, and Al in the range of 3:4 to 3:1.

In a still further embodiment of the amorphous silica product orabrasive blasting media comprises silicon oxide in the range of 50 wt. %to 75 wt. %. Iron oxides in the range of 25 wt. % to 55 wt. %, and otherfluxing compounds in the range of 0 to 10 wt. %. To further reduce themelting point, the other fluxes may be in the range of 1 wt. % to 10 wt.%. This embodiment of the amorphous silica product may comprise aluminumoxides in the range of 0.5 wt. % to 10 wt. %, zirconium oxides in therange of 0.5 wt. % to 10 wt. %, or a combination thereof to produce thedesired properties.

In another embodiment of the amorphous silica product or abrasiveblasting media comprises silicon oxide in the range of 50 wt. % to 75wt. %, a combination of iron oxides and one of aluminum oxides,zirconium oxides, or a combination of aluminum oxides and zirconiumoxides in the range of 25 wt. % to 60 wt. %, and other fluxing compoundsin the range of 0 to 15 wt. %. To further reduce the melting point, theother fluxes may be in the range of 1 wt. % to 15 wt. %.

Another embodiment is directed to an amorphous silica product or anabrasive blasting media consisting essentially of silicon oxide in therange of 50 wt. % to 75 wt. %, iron oxides in the range of 20 wt. % to40 wt. %; and fluxing compounds in the range of 0 to 15 wt. %.

Embodiments of the method are directed to a method of producing a glassproduct comprising preparing a melt batch, wherein the melt batchcomprises silicon oxide in the range of 55 wt. % to 75 wt. %, at leastone of iron, iron silicates, and iron oxides in the range of 18 wt. % to45 wt. %, and flux or fluxes in the range of 0 wt. % to 20 wt. %. Themelt batch is heated to melt the components a glass melt and cooling theglass melt. Cooling the glass melt may comprise quenching the glassmelt, air cooling the glass melt, annealing the glass melt orcombinations thereof.

In any embodiment, the melt batch consists essentially of silicon oxidein the range of 55 wt. % to 75 wt. %, at least one of iron, ironsilicates, and iron oxides in the range of 28 wt. % to 45 wt. %, andother flux components Sn the range of 0 5 wt. % to 10 wt. %.

A still other embodiment of the amorphous silica product or the abrasiveblasting media comprises silicon oxide in the range of 45 wt. % to 75wt. %, iron oxides in the range of 25 wt. % to 45 wt. %, and fluxingcompounds in the range of 0 to 10 wt. %. In some embodiments, theamorphous silica product or abrasive blasting media consists essentiallyof silicon oxide in the range of 45 wt. % to 75 wt. %, iron oxides inthe range of 28 wt. % to 45 wt. %, and fluxing compounds in the range of0 to 10 wt. %.

An abrasive blasting media comprising or, in some cases consistingessentially of silicon oxide in the range of 50 wt. % to 75 wt. %, ironoxides and aluminum oxides, wherein the iron oxides and the aluminumoxides together are in in the range of 5 wt. % to 50 wt. %, and fluxingcompounds in the range of 0 to 10 wt. %. For this embodiment, theabrasive blasting media may comprise the aluminum oxides in the range of3 to 10 wt. %.

An abrasive blasting media comprising or, in some cases consistingessentially of, silicon oxide in the range of 50 wt. % to 75 wt. %, ironoxides and aluminum oxides, wherein the iron oxides and the aluminumoxides together are in in the range of 25 wt. % to 50 wt. %, and fluxingcompounds in the range of 0 to 10 wt. %. Also, for this embodiment theabrasive blasting media may comprise the aluminum oxides in the range of3 to 10 wt. %.

The amorphous silica product or the abrasive blasting media maycomprise, or consist essentially of, silicon oxide in the range of 50wt. % to 75 wt. %, iron oxides and zirconium oxides, wherein the ironoxides and the zirconium oxides together are in in the range of 12 wt. %to 50 wt. %, and fluxing compounds in the range of 0 to 10 wt. %. Forthis embodiment, the zirconium oxides are in the range of 2 to 10 wt. %.

The amorphous silica product or the abrasive blasting media maycomprise, or consist essentially of, silicon oxide in the range of 50wt. % to 75 wt. %, iron oxides and zirconium oxides, wherein the ironoxides and the zirconium oxides together are in in the range of 25 wt. %to 50 wt. %, and fluxing compounds in the range of 0 to 10 wt. %. Forthis embodiment, the zirconium oxides are in the range of 2 to 14 wt. %.

In a still other embodiment, an amorphous silica product or abrasiveblasting media consists essentially of Silicon oxide in the range of 50wt. % to 75 wt. %, iron oxides in the range of 20 wt. % to 45 wt. %, andfluxing compounds in the range of 4 to 20 wt. %.

Embodiments also include methods of producing an amorphous silicaproduct or abrasive media. The method may comprise preparing a meltcomposition. Melt compositions of various compositions may be prepared.One embodiment of the melt composition comprises 50 wt. % to 75 wt. % ofsilicon oxides, 12 wt. % to 40 wt. % of iron oxide, and 4 wt. % to 20wt. % of at least one flux component. The melt composition may bereferred to as a “glass batch.” The term “glass batch” may refer to theraw materials fed into a batch furnace or a continuous furnace.

Another embodiment of the melt composition comprises 50 wt. % to 75 wt.% of silica, 12 wt. % to 40 wt. % of iron containing material, 4 wt. %to 20 wt. % of at least one flux component. In embodiments, the ironcontaining material may be at least one of iron oxides, non silicates,iron filings, or iron containing minerals. In such embodiments, the meltcomposition comprises 50 wt. % to 75 wt. % of silicon oxide, 10 wt. % to40 wt. % of iron containing metal filings, and 4 wt. % to 20 wt. % of atleast one flux component.

In some embodiments, the melt composition comprises or consistsessentially of 40 wt. % to 80 wt. % of collet and 8 wt. % to 60 wt. % ofat least one metal oxide. In these embodiments, the metal oxide may beat least one of iron oxide, aluminum oxide, zirconium oxide, titaniumoxide, magnesium oxide. The metal oxides may fee added individually, inalloys, or minerals comprising these metal oxides. As used herein, theterm “cullet” includes both process cullet and postconsumer cullet.

Further embodiments of the method of forming an amorphous silica productor abrasive comprise preparing a melt composition, wherein the meltcomposition comprises 50 wt. % to 75 wt. % of silica, 12 wt. % to 40 wt.% of a mix of metal oxides, and 2 wt. % to 20 wt. % of at least one fluxcomponent. In this embodiment, the silica may be amorphous silica(cullet, obsidian) or crystalline silica.

The methods may further comprise other glass manufacturing or fritmanufacturing process steps, such as, but not limited to, melting themelt composition in a furnace to form a melt, cooling the melt to form asolid product, crushing or otherwise comminuting the amorphous productto form particles and/or classifying the particles into particle sizeranges.

In any embodiment, the silicon oxides may include amorphous orcrystalline silicon oxides in the melt composition. The silicon oxidesmay be cullet, sand, stone, gravel, or other silica containing minerals,for example.

The basic and novel features of the invention are to prepare anamorphous silica product or abrasive blasting media that does notcomprise significant concentration of crystalline silica or other toxiccompounds for use in industrial, commercial, or residentialapplications.

In some embodiments, the amorphous silica product may comprisesignificant amounts of deleterious toxic compounds or heavy metals ifthey do not cause industrial hygiene problems during manufacture,transport or use.

In another embodiment, the process for producing amorphous productsconsists essentially of heating sand and/or a mineral comprisingcrystalline silica into at least one amorphous mass, cooling or allowingthe amorphous mass to cool, crushing or otherwise comminuting the siteof the amorphous mass into gravel, sand, or sift sized particles, andclassifying the sand, gravel, or silt sized particles into a desiredpanicle size distribution for use as an abrasive blasting media or inother products.

In another embodiment, the process for producing amorphous productsconsists essentially of heating sand and/or a mineral comprisingcrystalline silica to a temperature between the melting temperature andless than the gob temperature of the glass batch, quenching, cooling orallowing the amorphous mass to cool, reducing the size of into gravel,sand, or silt sized particles, and grading the gravel, sand, or siltsized particles into a desired particle size distribution for use as anabrasive blasting media or in other products.

Embodiments of the method of the present invention may not require thepost melt processing steps of glass making such as forming and floating,for example.

As such, embodiments of the method comprise preparing a glass batchcomprising crystalline silica, heating the glass batch or meltcomposition to produce a molten amorphous mass in a furnace, cooling thefurnace effluent such as by quenching the amorphous mass in a water bathor spray to produce amorphous silica mass or particles, optionally,further crushing the amorphous silica particles, and, optionally,annealing the amorphous silica particles.

The iron oxides or iron silicates, aluminum oxide or silicates, and/orthe zirconium oxides or silicates, for example, may be added to the meltcomposition or glass batch in the form of various sources Including daysand minerals.

The “amorphous sand” or other amorphous silica product could be formeddirectly into particles by fritting, for example, or formed into largermasses and crushed depending on the preferred method to obtain acommercially viable and advantageous product for various applications.

In certain embodiments, the properties of amorphous silica or sand maybe Improved for a specific application such as for use as a blastingmedia. Currently, there is no tailoring of recycled glass for blastingat this time. Since current amorphous silica blasting media wasoriginally produced for a different purpose (container or plate glass),the properties have not been tailored as a blasting media. The amorphousSilica blasting media could have the following properties, for example,if possible:

1) Specific gravity higher than crushed glass, for example, over 2.8(crushed glass is approximately 2.5, crystalline silica sand isapproximately 2.6); and 2) Hardness (mohs scale) approaching 7.0 to 7.5(crushed glass is 5.5 to 7, crystalline silica sand is approximately 5to 6) or a Knoop hardness above 650 or in certain embodiments above 680,for example.

At least one embodiment of the blasting media will be water soluble, sostabilizers such as calcium oxide, for example, are not required incertain embodiments as are typically added to the production ofcontainer glass and plate glass.

Typical particle sizes for blasting abrasives are in the range of meshsize 20/30, 30/70, and 50/100, for example. These mesh sizes may,typically, include 10% of the particles above or below the stated meshsize range.

Proppants may also be used and sold in various particle size ranges. Thetypically coarsest standard product for proppant is 20/40. (20/40particle size means that 90 percent of the proppant product is smallenough to pass through the 20 mesh screen having an opening of 0.85 mm)and large enough for greater than 90% of the particles to be retained onthe 40 mesh screen (0.425 mm). Each product allows for a distribution ofgrain sizes within the range. Other standard proppant sizes are 30/50,40/70, and 50/140 and are similarly defined. Embodiments of theproppants have particle sizes in the range of 20 to 140 mesh, furtherembodiments, include proppants having particles in the followingparticle size ranges 20/40, 30/50, 40/70, and 50/140. Further,embodiments of the method comprise melting the glass batch, crushing theamorphous solid, and classifying the particles in particle size rangeappropriate for use as a proppant. The particle size ranges appropriatefor use as a proppant include, but are not limited to, 20/24, 30/50,40/70, and 50/140, for example.

In further embodiments, appearance and opacity would not matter as muchas in a blasting material as in container or plate glass. Embodiments ofthe amorphous silica products may not have any transparency or clarityrestrictions. Constituents added to the batch to reach these propertiesmay make the glass opaque, ugly or unable to be formed by traditionalglass methods, for example.

Embodiments of the amorphous silica products should have no significantamounts of toxic components at sufficient quantities that would createinhalation hazards if used where human contact or inhalation isexpected. Blasting media comprising iron oxides have shown low toxicityin testing in contrast to the other abrasive blasting agents, forexample, the major component of specular hematite is iron oxide andspecular hematite produced no significant alterations in BAL levels ofLDH, numbers of lung PMN, macrophage chemiluminescence. the amount ofpulmonary hydroxyproline, or fibrotic score (Barnes Environmental, Inc.,1996). These findings are consistent with the low toxicity of iron oxidein most rat studies (Stokinger, 1984). A recent study in humans alsosuggests that the initial inflammation associated with intrapulmonaryinstillation of iron oxide resolves rapidly after exposure (Lay et al.,1999).

The glass batch and/or crystalline silica sand or rock need only beconverted to an amorphous silica, not fully melted. The cooling andcrushing processes may be designed for economy, to deliver the desiredproperties, and to provide ease with the production of sand sizedparticles in the desired particle size ranges. Embodiments of theprocess to produce amorphous glass products may be summarized as anefficient method of producing crushed, recycled glass particles withhigher density and improved hardness directly from crystalline silicamaterials for the same cost as recycle glass or from cullet to enhancethe properties for specific applications.

The production of a relatively high iron amorphous mineraloid can beperformed without more rigorous processes such as found in theproduction of soda lime glass. Embodiments of the method of forming theamorphous silica product may not require fining/viscosity reduction orannealing of container or flat glass.

As stated, the method may further comprise melting glass cullet. Incombination with property enhancing components. The property enhancingcomponents may comprise iron oxides, iron silicates, other materialscomprising iron, aluminum oxide, aluminum silicates, and other materialscomprising aluminum, zirconium oxide, zirconium silicates and/or othermaterials composing zirconium to produce an enhanced amorphous silicaproduct. The property enhancing components may provide an amorphoussilica product with higher hardness and/or higher density that typicalrecycled glass or glass cullet.

In a typical glass process, the silica does not melt but is solubilizedin the flux such as the melted sodium carbonate. Embodiments of theprocess Include replacing at least a portion of the calcium oxide (orcalcium carbonate) and the sodium carbonate. In container glass withiron, aluminum or similar materials as fluxes. The iron can come fromclays or iron oxides and the aluminum can come from aluminum oxide whichis abundant and cheap. There are aluminum silicates that also includeiron that may be added.

Embodiments of the method do not comprise or can eliminate the finingprocess step of container glass making and, further, may not need tocompletely melt the components as iron or other particles, bubbles, etc.are not detrimental to the product. Frit furnaces do not include afining process, for example.

Embodiments of the invention change soda lime glass composition bychanging fluxes to enhance density and hardness. Replacing sodiumcarbonate and calcium carbonate with oxides of iron and alumina, both ofwhich make excellent fluxes, should make a glass oxide product thatexhibits higher density and/or hardness than ordinary soda lime glass.

The glass batch and amorphous silica products are defined by theircomponents. However, zirconia (zirconium oxide) may be replaced withzirconia silicate, for example, on a zirconia equivalent substitution.The same molar amount of zirconium silicate may be added to the glassbatch or be present in this amorphous silica product to maintain theweight percentage of zirconium. Similarly, aluminum oxide may besubstituted for alumina silicate and iron silicate may be substitutedfor iron oxide.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by onehaving ordinary skill in the art to which this invention belongs. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure and will not be interpreted in an idealized or overlyformal sense unless expressly so defined herein.

In describing the invention, it will be understood that a number ofcomponents, parts, techniques and steps are disclosed. Each of these hasindividual benefit and each can also be used in conjunction with one ormore, or in some cases, all of the other disclosed embodiments andtechniques. Accordingly, for the sake of clarity, this description willrefrain from repeating every possible combination of the individualsteps in an unnecessary fashion. Nevertheless, the specification andclaims should be read with the understanding that such combinations areentirely within the scope of the invention and the claims.

DESCRIPTION

Embodiments of the invention include abrasive blasting media, proppants,and other amorphous silica products. The other amorphous silica productsinclude, but are not limited to, amorphous silica sands, gravel, orother particles. The abrasive blasting media, proppants, and amorphoussilica products may comprise other components that result in productswith the beneficial properties for the intended application or improvethe processing of the material.

An embodiment of the process comprises heating granules, grains, orparticles of sand, minerals, or rock comprising crystalline silica(hereinafter, “crystalline silica”) to a temperature where thecrystalline silica loses its crystalline structure and is transformedinto an amorphous silica. The amorphous silica is then cooled at asufficient rate to prevent recrystallization and, therefore, produce anamorphous silica sand, gravel, or other particle.

Embodiments of the method comprise heating any type of mineralcomprising crystalline silica to a temperature in which the crystallinesilica converts to amorphous silica form. The crystalline silica may bemixed with prior to or during the melting process with at least one ofmailing point reducing agents (fluxes), formers, stabilizers, densityincreasing components, hardness increasing components, toughnessincreasing components, or combinations thereof.

Another embodiment of the invention comprises adding additionalcomponents to amorphous silica, such as glass or cullet, to form a glassbatch and melting the glass batch to incorporate the additionalcomponents into the amorphous silica.

A further embodiment of the invention comprises adding recycled glass(cullet) to the crystalline silica sand or mineral and additionalcomponents to form the glass batch.

Preparing the Glass Batch or Melt Composition

Embodiments of the method comprise preparing a glass batch. There arethree general composition classifications of the glass batches; glassbatches comprising crystalline silica, glass batches comprisingamorphous silica or cullet, and glass batches comprising a combinationof crystalline silica and amorphous silica. The crystalline silica maybe obtained from minerals and sands, such as quartz, cristobalite andtridymite.

Crystalline Silica Glass Batches

The crystalline silica may be mixed with additional components, such as,but not limited to, melting point reducing agents (fluxes), formers,stabilizers, density increasing or decreasing components, hardnessincreasing or decreasing components, toughness increasing components, orcombinations thereof, for example.

The melting point of crystalline silica is high at about 1710° C. (3110°F.). Without special equipment such as induction furnaces and specialtymaterials, it is difficult to directly convert crystalline silica toamorphous silica. However, the melting point may be reduced by additionof at least one melting point reducing agent (flux). In someembodiments, preparing a glass batch comprises mixing the crystallinesilica containing material with at least one melting point reducingagent. Reducing the melting point of the glass batch may result. In amore efficient process that requires less energy to convert thecrystalline silica to amorphous silica. Melting point reducing agentsare compounds or elements that lower the temperature or temperaturerange that the crystalline silica is converted to amorphous silica ormelts first and solubilizes the crystalline silica.

In one embodiment, the glass batch may comprise, or consist essentially,of crystalline silica and at least one a metal, a metal oxide or a metalsilicate. For example, in one embodiment, the glass batch may comprisecrystalline silica in the range of 50 wt. % to 75 wt. % and at least oneof iron oxides or iron silicates in the range of 20 wt. % to 45 wt. %.The iron oxide acts as both a flux for the glass batch and to increasethe density of the amorphous silica product above the density of a pureamorphous silica or, in some embodiments, above the density of containerglass. To further reduce the melting point of the glass batch, the glassbatch may comprise additional fluxes. The additional fluxes may be in arange of 0 wt. % to 25 wt. %, for example, or in the range of 0 wt. % to12 wt. % in other embodiments.

In some cases, such as the addition of bauxite to the glass batch, onecomponent may comprise a combination of the crystalline silica, ironoxides, and additional metal oxides such as aluminum oxide. In anembodiment, the glass batch consists essentially of crystalline silicain the range of 50 wt. % to 75 wt. %, at least one of iron oxides oriron silicates in the range of 20 wt. % to 45 wt. %, and additionalfluxes may be in a range of 2 wt. % to 25 wt. %.

For some applications, the glass batch may comprise higherconcentrations of iron oxides, in another embodiment the glass batch maycomprise crystalline silica in the range of 50 wt. % to 70 wt. % and atleast one of iron oxides or iron silicates in the range of 30 wt. % to50 wt. %. Again, to further reduce the melting point of the glass batch,the glass batch may further comprise additional fluxes. The additionalfluxes may be in a range of 0 wt. % to 25 wt. %, for example, or in therange of 0 wt. % to 10 wt. % in other embodiments. In an embodiment, theglass batch consists essentially of crystalline silica in the range of50 wt. % to 70 wt. %, at least one of iron oxides or iron silicates inthe range of 30 wt. % to 50 wt. %, and additional fluxes may be in arange of 2 wt. % to 25 wt. %.

The composition of the amorphous silica product will be directly relatedto concentrations of the glass batch except the crystalline silica willbe in a predominantly amorphous state. The other components may also beamorphous and reported as oxides.

In another embodiment, the glass batch may comprise crystalline silicain the range of 50 wt. % to 70 wt. %, metal oxides or metal silicates inthe range of 30 wt. % to 50 wt. %, and additional fluxes in the range of0 wt. % to 25 wt. %. In another embodiment, the glass batch may comprisecrystalline silica in the range of 40 wt. % to 60 wt. %, metals or metaloxides or metal silicates in the range of 30 wt. % to 60 wt. %, andadditional fluxes in the range of 2 wt. % to 25 wt. %. In some cases,the metal oxides may be a combination of iron oxides with other metalsor metal oxides to alter the properties of the amorphous silica product.For example, the metal oxides may be aluminum oxides, zirconium oxides,a combination of aluminum oxides and iron oxides, a combination ofzirconium oxides and iron oxides, or a combination of aluminum oxides,zirconium oxides, and iron oxides. Similarly, in some cases, the metalsilicates may be a combination of iron silicates with other metals ormetal silicates to alter the properties of the amorphous silicaproducts. In some embodiments, the aluminum oxides or aluminum silicatesmay be present in a range from 0.5 wt. % to 10 wt. %. In someembodiments, the zirconium oxides or silicates may be present in a rangeof from 0.5 wt. % to 10 wt. %. In some additional embodiments, acombination of aluminum oxides and/or silicates and zirconium oxidesand/or silicates may be present in a range of from 0.5 wt. % to 10.

As such, an embodiment of the amorphous silica product comprisesamorphous silicon oxide in the range of 50 wt. % to 75 wt. %, acombination of iron oxides and aluminum oxides, wherein the iron oxidesand the aluminum oxides together are in in the range of 15 wt. % to 50wt. %, wherein the aluminum oxides are in a range of 0.5 wt. % to 10 wt.%., and fluxing compounds in the range of 0 to 10 wt. %. In a morespecific embodiment, the aluminum oxides may be in the range of 3 to 10wt. %.

Similarly, an embodiment of the amorphous silica product comprisesamorphous silicon oxide in the range of 50 wt. % to 75 wt. %, acombination of iron oxides and zirconium oxides, wherein the iron oxidesand the zirconium oxides together are in in the range of 12 wt. % to 50wt. %, wherein the zirconium oxides are in a range of 0.5 wt. % to 10wt. %, and fluxing compounds in the range of 0 to 10 wt. %. In a morespecific embodiment, the aluminum oxides may be m the range of 0.5 wt. %to 5 wt. %. In either of the above embodiments, the zirconium oxides orthe aluminum oxides may be substituted with 3 combination of aluminumoxides and zirconium oxides.

In one embodiment, the glass batch may comprise silica oxide in therange of 50 wt. % to 70 wt. %, iron oxides or iron silicates in therange of 27 wt. % to 47 wt. %; and fluxing compounds in the range of 2to 15 wt. %. In a similar embodiment, the glass batch may consistessentially of silicon oxide in the range of 50 wt. % to 70 wt. %, ironoxides or iron silicates in the range of 27 wt. % to 47 wt. %; andfluxing compounds in the range of 2 to 15 wt. %.

Such embodiments will result In an amorphous silica product comprisingsilicon oxide in the range of 50 wt. % to 70 wt. % and iron oxides inthe range of 27 wt. % to 47 wt. %. Other embodiments of the amorphoussilica product or abrasive blasting media will consist essentially ofsilicon oxide in the range of 50 wt. % to 70 wt. %, iron oxides in therange of 27 wt. % to 47 wt. %, and fluxing compounds in the range of 2to 15 wt. %.

Amorphous Silica Glass Batch

In one embodiment, the glass batch may comprise or consist essentiallyof amorphous silica and at least one metal or at least one metal oxide.For example, in one embodiment, the glass batch may comprise, amorphoussilica in the range of 40 wt. % to 75 wt. % and metal, metal silicates,and/or metal oxides in the range of 20 wt. % to 45 wt. %. In someembodiments, the metal or metal oxides may be iron oxides, ironsilicates, zirconium oxides, zirconium silicates, aluminum oxides,aluminum silicates, or combinations thereof. The other metals and metaloxides described herein may be components of other embodiments of theglass batches.

As in the crystalline silica glass batch, the iron oxide or ironsilicates acts as both a flux for the glass batch and to increase thedensity of the amorphous silica product above the density of a pureamorphous silica. To further reduce the melting point of the glassbatch, the glass batch may further comprise additional fluxes. Theadditional fluxes may be in a range of 0 wt. % to 25 wt. %, for example,or in the range of 0 wt. % to 10 wt. % in other embodiments.

Amorphous silica may foe added to the glass batch from various sources.The sources of the amorphous silica may be glass cullet, recycled glass,unprocessed glass waste, partially processed glass waste, diatomaceousearth, or combinations thereof. Glass cutlet, recycled glass and otherglass waste comprise amorphous silica and other components includingfluxes, stabilizers, formers, and colorants, for example. Therefore, theglass batch composition may account for the additional components in thesource of the amorphous silica. For example, cullet may comprise fluxesin the range of 10 wt. % to 20 wt. %. If the glass batch comprises 60%glass cullet, the amount of flux added into the glass batch with thecullet will be between 6 wt. % and 12 wt. %.

For some applications, the glass batch may comprise higherconcentrations of metals, metal silicates, or metal oxides. In anotherembodiment, the glass batch may comprise amorphous silica in the rangeof 40 wt. % to 70 wt. % and iron oxides in the range of 30 wt. % to 50wt. %. Again, to further reduce the melting point of the glass batch,the glass batch may further comprise additional fluxes. The additionalfluxes may be in a range of 0 wt. % to 18 wt. %, for example, or in therange of 0 wt. % to 10 wt. % in other embodiments. In an embodiment, theglass batch consists essentially of crystalline silica in the range of50 wt. % to 70 wt. %, iron oxides in the range of 30 wt. % to 50 wt. %,and additional fluxes may be in a range of 2 wt. % to 20 wt. %.

In another embodiment, the glass batch may comprise a silica in therange of 50 wt. % to 70 wt. %, metals, metal silicates, and/or metaloxides in the range of 30 wt. % to 50 wt. %, and additional fluxes inthe range of 0 wt. % to 25 wt. %. In one embodiment, the metals, metalsilicates, or metal oxides are iron, iron silicates, or iron oxides. Insome additional cases, the metal oxides may be a combination of ironoxides with other metals or metal oxides to alter the properties of theamorphous silica product. For example, the metal oxides may be aluminumoxides, zirconium oxides, a combination of aluminum oxides and ironoxides, a combination of zirconium oxides and iron oxides, or acombination of aluminum oxides, zirconium oxides, and iron oxides. Insome embodiments, the aluminum oxides may be present in a range from 0.5wt. % to 12 wt. %. In some embodiments, the zirconium oxides may bepresent in a range of from 0.5 wt. % to 12 wt. %. In some additionalembodiments, a combination of aluminum oxides and zirconium oxides maybe present in a range of from 0.5 wt. % to 10. At least a portion of themetal oxides may be substituted with metal silicates, for example.

As such an embodiment of the amorphous silica product produced fromamorphous sources of silica comprise amorphous silicon oxide in therange of 50 wt. % to 75 wt. %, a combination of iron oxides and aluminumoxides, wherein the iron oxides and the aluminum oxides together are inin the range of 15 wt. % to 50 wt. %, wherein the aluminum oxides are ina range of 0.5 wt. % to 10 wt. %., and fluxing compounds in the range of0 to 10 wt. %. In a more specific embodiment, the aluminum oxides may bein the range of 3 to 10 wt. %.

Similarly, an embodiment of the amorphous silica product comprisesamorphous silicon oxide in the range of 50 wt. % to 75 wt. %, acombination of iron oxides and zirconium oxides, wherein the iron oxidesand the zirconium oxides together are in in the range of 12 wt. % to 50wt. %, wherein the zirconium oxides are in a range of 0.5 wt. % to 10wt. %, and fluxing compounds in the range of 0 to 10 wt. %. In a morespecific embodiment, the aluminum oxides may be in the range of 0.5 wt.% to 5 wt. %.

In either of the above embodiments, the zirconium oxides or the aluminumoxides may be substituted with a combination of aluminum oxides andzirconium oxides.

Combinations of Amorphous Silica and Crystalline Silica

In some embodiments, the silica in the glass batch may be a combinationof crystalline silica and amorphous silica. In any of the aboveembodiments, the crystalline silica or the amorphous silica in the glassbatch may be replaced with a combination of amorphous silica andcrystalline silica in the stated compositional ranges. For example, theglass batch may comprise sand and glass cutlet, in other cases, thecrystalline silica may be from a crystalline silica mineral, such as theaddition of bauxite to the glass batch comprising cullet, the mineral,bauxite for example, may comprise a combination of the crystallinesilica, iron oxides, and additional fluxes such as aluminum oxide.

By processing the glass batches in either glass manufacturing methods orfrit manufacturing methods, amorphous glass products will be produced.The amorphous glass may be used for any purpose including, but notlimited to, abrasive blasting media, proppants, high density amorphousglass product, and other products Further embodiments of preparing aglass batch may include mixing the crystalline silica sand with recycledglass and/or cullet, if desired.

Heating the Glass Batch to Produce Amorphous Silica Products

Embodiments of the method comprise converting crystalline silica into anamorphous silica produce amorphous silica sand, gravel, or otherparticles. The method may comprise heating the glass batch comprisingcrystalline silica to a temperature above the temperature that resultsin the phase change from the crystalline silica to an amorphous form ofsilica. The furnace may increase the temperature of the glass batchabove the melting temperature of crystalline silica. The melting pointof pure silica dioxide is 3110° F. (1710° C.) but may be lowered byaddition of fluxes as described above.

Embodiments of the heating the glass batch comprise feeding the glassbatch into a glass melting furnace. The furnace may be a continuous orbatch furnace. There are various types of glass melting furnacesincluding pot furnaces (for batch processing), day tank furnaces, gasfired furnaces, and electric furnaces.

In an embodiment comprising a continuous furnace, the glass batch may beheated to and become molten at approximately 1100° C. to 1700° C., morespecifically a temperature range 1300° C. to 1600° C., depending uponthe composition of the glass batch. In some embodiments of the method,the glass batch may be heated to or above the melt temperature of theglass batch. In another embodiment, the glass batch may be heated to atemperature between the melt temperature and the temperature in whichthe crystalline silica converts to amorphous silica. As previouslydescribed, the melt temperature and the temperature at which thecrystalline silica converts to amorphous silica will depend on thecomposition of the glass batch. In such embodiments, the glass batch maybe heated to a temperature below the gob temperature. In certain batchembodiments, the glass batch may be heated to similar temperatures. Incertain embodiments, the process does not comprise refining the moltenglass batch to remove all gas bubbles. This process is necessary toproduce clear glass containers or plate glass but may not be necessaryto produce amorphous silica sand, gravel, and other particles.

Alternatively, a further embodiment of the process comprises heatinggranules, grains, or particles of sand or rock comprising crystallinesilica Individually in combination with the other steps describedherein. In further embodiments, the furnace may be a rotating kilnfurnace.

The effluent of the furnace may be a ribbon of molten amorphous silica.

Cooling the Furnace Effluent

Embodiments of the method of the invention comprise cooling the ribboneffluent from the furnace. Therefore, a method may comprise cooling orallowing the amorphous mass cool to a hardened state. In someembodiments, the process may comprise rapidly cooling or quenching theribbon of furnace effluent such as by fritting. Fritting of the moltenglass causes a thermal gradient and violent fracturing of thesolidifying amorphous material. The quenching of the molten glass may beperformed by contact with a fluid such as water. The molten glass ribbonmay overflow the furnace into a bath of fluid or the fluid may bespraying of the molten glass.

The solidified solid is an amorphous silica product. The fracturing ofthe glass results in small particles that may be classified intoparticle size ranges. The various particle size ranges may findapplication in the products described herein.

Embodiments of the method may further comprise crushing or otherwisecomminuting at least a portion of the amorphous silica to particles to asmaller size or to narrow the particle size distribution. The deseedparticle size distribution may be the appropriate particle sizedistribution for abrasive blasting, use In mortar, plaster, concrete,and asphalt paving, foundry sand, and/or the production of bricks, forexample.

Optionally, an embodiment of the process may comprise annealingfractured amorphous silica particle or the crushed or otherwisecomminuted amorphous mass.

The molten glass batch exits the refractory through a weir The weir isdesigned to provide an evenly shaped flow of molten glass for quenching.The furnace may have more than one weir to ensure proper molten glassribbon shape and size for efficient quenching and fracturing of thesolidifying amorphous silica.

In certain embodiments, quenching the molten amorphous mass should beperformed properly to ensure fracturing of the amorphous solid uponrapid cooling. Ideally, the quenched amorphous solid comprises aparticulate product having a desired particle size range, averageparticle size, and/or particle size distribution. The furnace effluentflow rate and shape may be controlled to provide uniform quenching ofthe amorphous silica.

Applications and Products

An embodiment of a process consists essentially of transformingcrystalline or polycrystalline sand, grains, particles, or rock intoamorphous sand, gravel or other particles for the purpose of renderingthe material substantially free of crystalline silica (a knowncarcinogen) making it a safe replacement for naturally occurringproducts containing various forms of crystalline silica in consumer andindustrial applications through a process comprising heating thecrystalline or polycrystalline sand, grams, particles or rock into anamorphous mass and reducing the size of the amorphous mass for use inthe desired application.

Still further embodiments of the process may comprise using amorphoussand for applications that currently of previously used crystalline orpolycrystalline sand products including, but not limited to silica sandproduct applications and crushed rock products.

The amorphous sand produced by this process are especially useful forprocesses that produce airborne sand products such as for abrasiveblasting or products that will be cut such as cement blocks, pavers, orbricks to avoid producing a potentially dangerous dust if crystallinesilica sand was used.

Products and applications for the amorphous silica particles include butare not limited to, crystalline silica free amorphous silica sand,crystalline silica free amorphous silica gravel, crystalline silica freeamorphous cullet, amorphous silica blasting material, crystalline silicafree concrete, grout, manufactured stone, pavers, or mortar, concreteblocks made from crystalline silica free concrete, crystalline silicafree bricks comprising crystalline free amorphous silica. For example,the bricks may comprise crystalline silica free sand in a concentrationfrom 50% to 60% by weight, alumina in a concentration from 20% to 30% byweight, and lime in a concentration from 2 to 5% by weight.

The amorphous silica of the invention may be used as water insoluble orwater soluble sand and blasting media.

Unlike recycled glass products, the amorphous silica sand produced bythe method of the invention will comprise no trace fecal matter, notrace ferrous matter (unless intentionally added), no trace nonferrousmetals, no trace stone or ceramic, and/or no trace pathogens. Thesesubstances are found in all recycled glass products.

Another embodiment of the method of the present invention to directlycreate a glass collet that is free from contaminants. Glass productionfacilities add crushed recycled glass cutlet into the new glassproduction process to reduce the heat requited to melt the silica sandand the melt temperature of the silica sand. The problem with this glasscullet is that it may include contaminants from the glass recycleprocess. An embodiment of the method of the present invention is toproduce dean glass culler directly from crystalline silica sand. This“pre-reacted” batch material that can be added to batch glass (much asglass cullet is used today) that will lower the melt temperature ofbatch glass.

The amorphous silica sand, gravel, or other particles may be used in themanufacture of many products. For example, crystalline free silica foamglass and ceramics may be produced. An embodiment of the method forproduction of crystalline free foamed glass may compose blending fineamorphous silica sand or ground amorphous silica sand with a blowingagent to form a foam glass precursor. The blowing agent may be anycompound that produces an off-gas during heating at furnacetemperatures. The blowing agent may be, but is not limited to, carbon orlimestone, for example.

The method may further comprise heating the foam glass precursor in thefurnace to cause the blowing agents to out-gas, thus expanding orfoaming the molten mass. The molten mass is cooled and annealed tofreeze the gas packets creating a lightweight product. Foamed glass inthe melted state can be formed into many products Including insulation,blocks, brick, or aggregate for construction or agriculture.

The new “virgin” amorphous silica glass cullet product would competedirectly with recycled glass collet. The advantage of the embodied“pre-reacted” batch material would be it would be 100% free ofdeleterious materials such as rock, ceramic, metals, or lead that culletproducers go to a lot of work to ensure don't get into their collet inexcessive quantities.

As used herein, the term “no trace” means that the component is belowmeasurement limits of instruments typically used to determine theconcentration of the component.

As used herein, “amorphous silica sand” means a silica productcomprising less than 2 wt. % of crystalline silica in a primarilyamorphous silica product, in a more specific embodiment, “amorphoussilica sand” means a silica product comprising less than 1 wt. % ofcrystalline silica in a primarily amorphous silica product; and in aneven more specific embodiment for blasting products, for example,“amorphous silica sand” means a silica product composing less than 0.5wt. % of crystalline silica in a primarily amorphous silica product.

Stabilizers may be added to the glass batch to reduce the watersolubility of the resultant amorphous silica products. Stabilizersinclude, but are not limited to, calcium carbonate (lime), for example.Other components that may be mixed with the crystalline silica toproduce the glass batch include a number of metal oxides to producedesired properties in the amorphous silica products For example, alumina(Al2O3) may be added to the glass batch to provide increased durabilityof the amorphous silica products produced from the glass batch. Boronoxide (B2O3) may be a glass former like silica and increases thechemical resistance of the glass.

The molting point reducing agents may include, but is not limited to,sodium carbonate, sodium nitrate, iron oxide, iron silicates, potash,potassium carbonate, calcium carbonate, colemanite, sodium oxide,calcium oxide, magnesia, rubidium, aluminum oxides, alumina silicates,lead oxide, alkali metals, lithium, sodium, potassium, rubidium, cesium,francium, and combinations thereof.

Additional fluxes may include materials such as naturally occurringproducts that contain these reducing agents such as, but not limited to,feldspar, alumina silicates comprising iron, bauxite, days, ball clays,Kentucky or Tennessee clay, and kaolin, for example. Clay may be afinely grained natural rock or sod material that combines one or moreclay minerals with possible traces of quartz (SiO2), metal oxides(Al2O3, MgO etc.) and organic matter. Ball clays are typicallykaolinitic sedimentary clays that commonly consist of 20-80% kaolinite,10-25% mica, 6-65% quartz. Another flux may be bauxite.

For example, sodium carbonate and potassium carbonate may lower themelting point of crystalline silica to about 1,000° C. (1830° F.) incertain concentrations and may be added to make the melting process moreefficient.

Sodium carbonate increases the viscosity of the glass melt at a giventemperature but is relatively expensive Additionally, mixing sodiumcarbonate into the crystalline silica glass batch (and/or anothermelting point reducing agent), without the addition of a stabbing agentsuch as, but not limited to lime, may cause the amorphous silicaproducts to be at least slightly water soluble. Water soluble amorphoussilica products may be more environmentally friendly that insolubleamorphous silica. Thus, a method of producing a water-soluble amorphoussilica sand, gravel, or other particles comprises mixing a temperaturereducing agent with crystalline silica without the addition of astabilizer such as calcium carbonate and melting the batch glass toproduce an amorphous silica product to be water soluble.

Density and Hardness Affecting Components

Embodiment of the amorphous silica products may comprise metals or metaloxides. These metals and metal oxides include refractory metals, iron,titanium, vanadium, chromium, manganese, zirconium, zircon, niobium,molybdenum, ruthenium, rhodium, hafnium, tantalum, tungsten, rhenium,osmium, iridium, and oxides or silicates of these metals, for example.

Additional metals include aluminum, aluminum oxides, aluminum silicates.The alumina may be from clay and, in some embodiments, low alkali clay.Some clays are up to 10% alumina

Embodiments of the amorphous silica products may comprise componentsthat change the hardness of the resultant amorphous silica products.Alkalis and lead oxides will decrease hardness in the resultantamorphous product, whereas addition of CaO, MgO, ZnO, Al2O3, B2O3,zirconium, zircon, zirconium oxides, iron and iron oxides will result inamorphous silica products with greater hardness.

EXAMPLES

Cullet was obtained from a glass recycling facility. The composition ofthe cutlet was approximately as follows:

Typical Cullet Composition SiO2 74. w.t % MgO 0.3 wt. % CaO 11.3 wt. % NaO  13 wt. % K2O 0.2 wt. % Al2O3 0.7 wt. % Fe2O3 0.01 wt. % 

In embodiments of the glass formulations, the silicon oxides may beadded in the form of cullet, sand, other sources of silicon oxides, orcombinations thereof.

The melts were performed in a (Make and Model of furnace)

Example 1

A melt batch (Sample 2789) was prepared comprising the followingcomposition, silica dioxide (SiO2) at 85 wt. %, sodium oxide (NaO) at 14wt. %, and iron oxide (Fe2O3) at 1 wt. % in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately 1525° C. The melted batch was then quenched in water. Thesolidified glass was sent for analysis for specific gravity andhardness. The specific gravity was determined to be 2.25. The Knoophardness was determined to be 481.8.

Example 2

A melt batch (Sample 2790) was prepared composing the followingcomposition, silica dioxide (SiO2) at 84 wt. %, zirconium oxide (ZrO) at13 wt. %, sodium oxide (NaO) at 1 wt. %, and iron oxide (Fe2O3) at 2 wt.% in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately 1550° C. The melted batch was then quenched in water. Thesolidified glass was sent for analysis for specific gravity andhardness. The specific gravity was determined to be 2.36. The Knoophardness was determined to be 493.7

Example 3

A melt batch (Sample 2791) was prepared comprising the followingcomposition, silica dioxide (SiO2) at 83 wt. %, zirconium oxide (ZrO) at2 wt. %, sodium oxide (NaO) at 10 wt. %, and iron oxide (Fe2O3) at 5 wt.% in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately 1575° C. The melted batch was then quenched in water. Thesolidified glass was sent for analysis for specific gravity andhardness. The specific gravity was determined to be 2.35 The Knoophardness was determined to be 540.6.

Example 4

A melt batch (Sample 2792) was prepared comprising the followingcomposition, silica dioxide (SiO2) at 80 wt. %, zirconium oxide (ZrO) at5 wt. %, sodium oxide (NaO) at 5 wt. %, and iron oxide (Fe2O3) at 10 wt.% in the melt batch.

The melt hatch was melted in a crucible in a batch furnace atapproximately 1625° C. The melted batch was then quenched in water. Thesolidified glass was sent for analysis for specific gravity andhardness. The specific gravity was determined to be 2.86. The Knoophardness was determined to be 638.4.

Example 5

A melt batch (Sample 2799) was prepared comprising the followingcomposition, silica dioxide (SiO2) at 70 wt. %, zirconium oxide (ZrO) at2 wt. %, sodium oxide (NaO) at 5 wt. %, aluminum oxide (Al2O3) at 3 wt.%, and iron oxide (Fe2O3) at 20 wt. % in the melt batch.

The melt batch was melted in a crucible In a batch furnace atapproximately 1600 to 1625° C. The melted batch was then quenched inwater. The solidified glass was sent for analysis for specific gravityand hardness. The specific gravity was determined to be 2.5. The Knoophardness was determined to be 615.4.

Example 6

A melt batch (Sample 2800) was prepared comprising the followingcomposition, silica dioxide (SiO2) at 65 wt. %, zirconium oxide (ZrO) at2 wt. %, sodium oxide (NaO) at 4 wt. %, aluminum oxide (Al2O3) at 6 wt.%, and iron oxide (Fe2O3) at 23 wt. % in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately 1600 to 1625° C. The melted batch was then quenched inwater. The solidified glass was sent for analysis for specific gravityand hardness. The specific gravity was determined to be 2.69. The Knoophardness was determined to be 668.7.

Example 7: Melt Batch from Sand

A melt batch (Sample 2801) was prepared comprising the followingcomposition, silica dioxide (SiO2) at 60 wt. %, zirconium oxide (ZrO) at2 wt. %, sodium oxide (NaO) at 3 wt. %, aluminum oxide (Al2O3) at 8 wt.%, and iron oxide (Fe2O3) at 27 wt. % in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately 1600 to 1625° C. The melted batch was then quenched inwater. The solidified glass was sent for analysis for specific gravityand hardness. The specific gravity was determined to be 2.52. The Knoophardness was determined to be 721.9.

Example 8: Melt Batch from Cullet

A melt batch (Sample 2802) was prepared comprising the followingcomposition, cullet (approximate composition above) at 90 wt. %,zirconium oxide (ZrO) at 2 wt. %, aluminum oxide (Al2O3) at 3 wt. %, andiron oxide (Fe2O3) at 5 wt. % in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately 1600 to 1625° C. The melted batch was then quenched inwater. The solidified glass was sent for analysis for specific gravityand hardness. The specific gravity was determined to be 2.50. The Knoophardness was determined to be 622.

Example 9: Melt Batch from Cullet

A melt batch (Sample 2803) was prepared comprising the followingcomposition, cullet (approximate composition above) at 80 wt. %,zirconium oxide (ZrO) at 3 wt. %, aluminum oxide (Al2O3) at 4.5 wt. %and iron oxide (Fe2O3) at 12.5 wt. % in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately 1600 to 1625° C. The melted batch was then quenched inwater. The solidified glass was sent for analysis for specific gravityand hardness. The specific gravity was determined to be 2.54. The Knoophardness was determined to be 651.9.

Example 10: Melt Batch from Collet

A melt batch (Sample 2804) was prepared comprising the followingcomposition, cullet (approximate composition above) at 70 wt. %,zirconium oxide (ZrO) at 4 wt. %, aluminum oxide (Al2O3) at 6 wt. %, andiron oxide (Fe2O3) at 20 wt. % in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately 1600 to 1625° C. The melted batch was then quenched inwater. The solidified glass was sent for analysis for specific gravityand hardness. The specific gravity was determined to be 2.71. The Knoophardness was determined to be 654.8.

Example: 11: Melt Batch from Sand

A melt batch (Sample 2809) was prepared comprising the followingcomposition, silica dioxide (SiO2) at 62.45 wt. %, magnesium oxide (MgO)at 0.3 wt. %, calcium oxide (CaO) at 0.2 wt. %, sodium oxide (NaO) at 7wt. %, potassium oxide (KO) at 0.05 wt. %, and iron oxide (Fe2O3) at 30wt. % in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately YYYY° C. A portion of the melted batch was then quenchedin water (Sample XXXXQ) and a portion of the melted batch was air cooled(Sample 2809A).

The solidified glass was sent for analysis for specific gravity andhardness. The specific gravity for Sample 2809Q was determined to be2.534 and its Knoop hardness was determined to be 552.1.

The specific gravity for Sample 2809A was determined to be 2.864 and itsKnoop hardness was determined to be 570.6.

Example 12: Melt Batch from Sand

A melt batch (Sample 2810) was prepared comprising the followingcomposition, silica dioxide (SiO2) at 57.45 wt. %, magnesium oxide (MgO)at 0.3 wt. %, calcium oxide (CaO) at 0.2 wt. %, sodium oxide (NaO) at6.14 wt. %, potassium oxide (KO) at 0.05 wt. %, and iron oxide (Fe2O3)at 35 wt. % in the melt batch.

The melt batch was melted in a crucible in a batch furnace atapproximately YYYY° C. A portion of the melted batch was then quenchedin water (Sample 2810Q) and a portion of the melted batch was air cooled(Sample 2810A).

The solidified glass was sent for analysis for specific gravity andhardness. The specific gravity for Sample 2810Q was determined to be2.858 and its Knoop hardness was determined to be 580.8.

The specific gravity for Sample 2810A was determined to be 2.826 and itsKnoop hardness was determined to be 586.4.

Example 12

A melt batch may be prepared comprising the following composition,silica dioxide (SiO2) at 42.3 wt. %, magnesium oxide (MgO) at 0.3 wt. %,calcium oxide (CaO) at 0.2 wt. %, sodium oxide (NaO) at 6.14 wt. %, wt.%, and iron oxide (Fe2O3) at 50 wt. % in the melt batch.

The embodiments of the described amorphous silica products and methodare not limited to the particular embodiments, components, method steps,and materials disclosed herein as such components, process steps, andmaterials may vary. Moreover, the terminology employed herein is usedfor the purpose of describing exemplary embodiments only and theterminology is not intended to be limiting since the scope of thevarious embodiments of the present invention will be limited only by theappended claims and equivalents thereof.

Therefore, while embodiments of the invention are described withreference to exemplary embodiments, those skilled in the art willunderstand that variations and modifications can be affected within thescope of the invention as defined In the appended claims. Accordingly,the scope of the various embodiments of the present invention should notbe limited to the above discussed embodiments and should only be definedby the following claims and all equivalents.

1. An abrasive blasting media, comprising: silicon oxide in the range of50 wt. % to 75 wt. %; iron oxides in the range of 20 wt. % to 45 wt. %;and fluxing compounds in the range of 0 to 25 wt. %.
 2. The abrasiveblasting media of claim 1, comprising aluminum oxides In the range of0.5 wt. % to 10 wt. %.
 3. The abrasive blasting media of claim 1,comprising zirconium oxides in the range of 0.5 wt. % to 10 wt. %. 4.The abrasive blasting media of claim 1, wherein the fluxing compoundsare selected from the group comprising sodium oxides, calcium oxides,magnesium oxides, potassium oxides, lithium oxides, boric oxides, andcombinations thereof.
 5. The abrasive blasting media of claim 1, whereinthe ratio of Si to Fe in the abrasive blasting media is in the range of3:4 to 4:1.
 6. The abrasive blasting media of claim 1, wherein the ratioof Si to Fe in the abrasive blasting media is in the range of 3:4 to3:1.
 7. The abrasive blasting media of claim 1, wherein the iron oxidesare in the range of 20 wt. % to 45 wt. %.
 8. The abrasive blasting mediaof claim 1, wherein the iron oxides are in the range of 20 wt. % to 30wt. %.
 9. The abrasive blasting media of claim 8, wherein the fluxingcompounds comprise sodium oxide and are in the range of 2 wt. % to 10wt. % of the abrasive blasting media.
 10. An abrasive blasting media,consisting essentially of: silicon oxide in the range of 50 wt. % to 80wt. %; iron oxides in the range of 18 wt. % to 40 wt. %; and fluxingcompounds In the range of 1 wt. % to 10 wt. %.
 11. The abrasive blastingmedia of claim 1, wherein the fluxing compounds are selected from thegroup comprising sodium oxides, calcium oxides, magnesium oxides,potassium oxides, lithium oxides, boric oxides, and combinationsthereof.
 12. The abrasive blasting media of claim 10, wherein the ironoxides are in the range of 18 wt. % to 30 wt. % and the silicon oxidesare in the range of 55 wt. % to 80 wt. %. 13 An abrasive blasting media,consisting essentially of: silicon oxide in the range of 50 wt. % to 70wt. %; iron oxides in the range of 18 wt. % to 30 wt. %; a combinationof aluminum oxides and zirconium oxides In the range of 3 wt. % to 15wt. %; and fluxing compounds in the range of 1 wt. % to 14 wt. %. 14.The abrasive blasting media of claim 13, wherein a combination ofaluminum oxides and zirconium oxides in the range of 4 wt. % to 11 wt.%.
 15. The abrasive blasting abrasive of claim 14, wherein the abrasiveblasting abrasive has a Knoop hardness greater than
 630. 16. Theabrasive blasting abrasive of claim 14, wherein the abrasive blastingabrasive has a Knoop hardness greater than
 650. 17. The abrasiveblasting abrasive of claim 14, wherein the abrasive blasting areparticles having a particle size range wherein greater than 80% of theparticles are in a size range from 425 microns to 2000 microns.
 18. Theabrasive blasting abrasive of claim 14, wherein the abrasive blastingabrasive has a density greater than 2.8 and less than 3.5.
 19. Theabrasive blasting media of claim 14, wherein the zirconium is less than3 wt. %. 20.-75. (canceled)